Particulate separator for production wells

ABSTRACT

Disclosed in a particulate separator for use with a petroleum production well that produces a fluid mixture including particulate matter. The separator includes an outer casing and an inner pipe disposed within the outer casing. The outer casing includes fluid intake slots extending through its sidewall near is upper end. Fluid entering the outer casing flows downward along a flow path between the outer casing and a lower open end of the inner pipe. A fin on a lower portion of the inner pipe imparts a radial motion to the downwardly flowing fluid, which forces particulates toward the inside surface of the outer casing. In an arrangement, the outer casing has an upper portion and a lower portion that overlaps the fin. In an arrangement, a sidewall thickness of the lower portion of the casing is greater than a sidewall thickness of the upper portion of the outer casing.

CROSS REFERENCE

The present application claims the benefit of the filing date of U.S. Provisional Application No. 62/823,270 having a filing date of Mar. 25, 2019, the entire contents of which is incorporated herein by reference.

FIELD

The present disclosure is directed to oil and/or gas wells and more particularly to the removal of particulates, such as sand, from production streams of such wells.

BACKGROUND

Oil and gas wells can be naturally flowing, injecting or can be produced by any means of artificial lift. Particulates within a production stream of such wells, which can include both liquid and gaseous products, can be both naturally occurring and manmade. Naturally occurring particulates can include sand, silt, and other solids, which may be natural byproducts of a producing well. As hydrocarbons and water flow through the formation, these particulates are carried in the flow stream and can be carried into the production tubing which can cause problems within the tubing and/or with an artificial lifting mechanism such as an electric submersible pump.

Manmade particulates are often introduced into a well via hydraulic fracturing (e.g., fracking), which is commonly utilized to increase well production. Such a procedure involves injecting large quantities of water, sand (e.g., fracture proppant), and chemicals under high hydraulic pressure into a bedrock formation (e.g., production formation) via the well bore. The process is intended to create new fractures in the formation as well as increase the size of any existing fractures. These fractures allow more production fluids to exit the formation increasing the production of the well. The sand, known as fracture proppant, flows into fractures under high hydraulic pressure and props these fractures open after removal of the high hydraulic pressure. That is, some of the fracture proppant remains trapped within the fractures to hold these fractures open. However, a portion of the introduced fracture proppant remains free within the well. Such fracture proppant may be included within the production stream of the well during production.

Natural or manmade particulates (e.g., fracture proppant) can cause a multitude of problems for oil and gas operators during production. For example, in flowing wells abrasive particulates can “wash through” metals in piping creating leaks and potentially hazardous conditions. Particulates can also fill-up or otherwise plug surface flow lines, vessels, and tanks. In wells using artificial lift, production of particulates can reduce of the life of the down-hole assembly (e.g., electric submersible pumps) and increase maintenance costs.

SUMMARY

One arrangement of the disclosure is directed to a particulate separator for use with a petroleum production well that produces a fluid mixture including particulate matter. The separator includes an outer casing and an inner pipe disposed within the outer casing. The outer casing is sized for receipt within a well bore and includes intake slots toward its upper end allowing a fluid mixture to enter the space between the outer casing and the inner pipe (e.g., from the well bore) and flow downward toward a pump intake formed by a lower end of the inner pipe. An upper end of the inner pipe may be fluidly attached to a pump (e.g. electric submersible pump). A lower outside portion of the inner pipe includes at least one fin (e.g., helical) to impart a radial motion to the downwardly flowing fluid, which forces particulates toward the inside surface of the outer casing. Fluid is drawn upward into an open bottom end of the inner pipe, which is typically disposed at or near an interior centerline of the outer casing. Drawing from at or near the centerline of the outer casing allows heavier particles disposed nearer to the inside surface of the outer casing (e.g., due to the radial motion of the fluid) to continue through a bottom end of the separator. In an arrangement, the properties of the outer casing varies over its length.

In one arrangement, a sidewall thickness of the outer casing varies over its length. More specifically, a portion of the outer casing that encases or overlaps the portion of inner pipe imparting radial motion on the fluid flow has a greater thickness than a portion of the casing that does not overlap this portion of the inner pipe. In a further arrangement, the outer casing includes an upper tube or barrel and a lower tube or barrel having a common inside diameter and different outside diameters. In such an arrangement, the lower tube having an increased outside diameter may overlap the portion of the inner pipe that imparts radial motion to the fluid flow.

In another arrangement, a sidewall property of the outer casing varies over its length such that a portion of the outer casing that encases or overlaps the portion of inner pipe imparting radial motion on the fluid flow has a different material type and/or hardness than a than a portion of the outer casing that does not overlap this portion of the inner pipe.

In a further arrangement, various components of the separator may be threadedly assembled. In such an arrangement, individual components may be replaced when worn without requiring the replacement of other components.

DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram of a first embodiment of a well and pump.

FIG. 2 is a diagram of a second embodiment of a well and pump.

FIG. 3A illustrates a side view of a separator in accordance with the present disclosure.

FIG. 3B illustrates a cross-sectional side view of the separator of FIG. 3A.

FIG. 3C illustrates an exploded view of the separator of FIG. 3A.

FIG. 4 illustrates a side view of a top connector for use with the separator of FIG. 3A.

FIG. 5 illustrates a side view of a bottom connector for use with the separator of FIG. 3A.

FIG. 6 illustrates dimensional differences between an upper and lower barrel of an outer casing of a separator in accordance with the present disclosure.

DETAILED DESCRIPTION

Reference will now be made to the accompanying drawings, which at least assist in illustrating the various pertinent features of the presented inventions. The following description is presented for purposes of illustration and description and is not intended to limit the inventions to the forms disclosed herein. Consequently, variations and modifications commensurate with the following teachings, and skill and knowledge of the relevant art, are within the scope of the presented inventions. The embodiments described herein are further intended to explain the best modes known of practicing the inventions and to enable others skilled in the art to utilize the inventions in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the presented inventions.

Referring now to FIG. 1, a diagram of a typical sucker rod pump used in oil wells is described. The sucker rod pump is described only for the purposes of illustrating the operation of a typical oil well and is not intended to be limiting in any manner as the presented disclosure is applicable to any producing oil well including those using any means of artificial lift, such as rod pumping, electric submersible pumps, progressive cavity, and other methods.

As shown in FIG. 1, a well 10 includes a well bore 11 and a pump assembly 12. In this embodiment, the pump assembly 12 is formed by a motor 13 that supplies power to a gear box 14. Gear box 14 is operable to reduce the angular velocity produced by the motor 13 and to increase the torque relative to the input of the motor 13. The input of the motor 13 is used to turn a crank 15 and lift a counter weight 16. As the crank 15 is connected to a walking beam 17 via a pitman arm 18, the walking beam 17 pivots and submerges a plunger 19 in well bore 11 using a bridle 20 connected to the walking beam 18 by a horse head 21. The walking beam 17 is supported by a Sampson post 22. The well bore 11 includes a casing 23 and a production tubing 24 extending inside the casing 23. A sucker rod 25 extends through the interior of the production tubing 24 to the plunger 19. At the bottom 25 of well bore 11 in oil bearing region 26, the casing 23 includes perforations 27 that allow hydrocarbons and other material to enter an annulus 28 between the casing 23 and the production tubing 24. Gas is permitted to separate from the liquid products and travel up the annulus where it is captured. Liquid well products collect around a pump barrel 29, which contains standing a valve 30. In this embodiment, the plunger 19 includes a traveling valve 31. During the down stroke of the plunger, the traveling valve is opened and product in the pump barrel is forced into the interior of the tubing 24. When the pump begins its upstroke, the traveling valve 31 is closed and the material in the tubing is forced up the tubing by the motion of plunger 19. Also, during the upstroke, the standing valve 30 is opened and material flows from the annulus in the oil bearing region and into the pump barrel.

As can be seen from FIG. 1, where the product flowing into the well bore may contain sand and other particles, those particles can enter the pump and plug or cause damage to the pump mechanism, as well as the casing and tubing and above ground lines and tanks. Where sand and/or other particles are mixed into the product, as can occur naturally or through fracking, it would be helpful to have a mechanism for separating the sand and particulates from the hydrocarbon product. The present disclosure provides a separator mechanism for separating particulate matter from the well product. Such a device may be incorporated into a typical sucker rod pump as illustrated in FIG. 1. Such as device is disclosed herein and may be disposed below the pump (not shown) as illustrated in FIG. 1.

Referring now to FIG. 2, an embodiment of a down-hole sand separator according to the concepts described herein is shown used in a production well incorporating an electrical submersible pump. A well 40 is formed by a casing 44 and production tubing 45 and further includes a submersible pump 80 and electrical motor 82 (not to scale). In application, electrical power cables from a surface power source would extend into the well to the electrical motor 82. The power cables are omitted for purposes of clarity. Disposed beneath the pump 80 is a separator 50 for removing gas and solids such as sand from a production flow. In the illustrated embodiment, a torque anchor 47 prevents the motor 82 from turning within the casing 44. A mud anchor 5 serves as a catch area for any foreign matter or solids removed from the production fluid.

FIGS. 3A-3C illustrate a down-hole separator 150 that may be incorporated into the wells described above to separate particulates from a production stream. More specifically, FIGS. 3A and 3B show a side view and a side sectional view of the separator, respectively, while FIG. 3C shows an exploded perspective view of the separator 50. The separator 50 is generally defined by an outer casing 100 that is sized for receipt within a well bore. In the illustrated embodiment, the outer casing is shown as having an upper casing 102A (e.g., upper barrel) and a lower casing 102B (e.g., lower barrel) that are connected end to end. The upper and lower casings may be treaded together where one component includes internal threads and the other component includes internal treads. Alternatively, a pipe collar (not shown) may receive external threads of both components. However, it will be appreciated that other embodiments may utilize a single piece casing. Various couplings 170, 172 attach an inner pipe 120 within the interior of the outer casing 100. As illustrated in FIGS. 3B and 3C, the inner pipe 120 is disposed concentrically within the interior of the outer casing 100 such that a space (e.g., annulus) is formed between an outside surface of the inner pipe 120 and an inside surface of the outer casing. These components work together to separate particulates from a production stream.

As best illustrated in FIG. 3B, production fluids enter an upper portion of the separator 50 through intake slots 112 formed through a sidewall in an upper portion of the outer casing 100. That is, production fluids within the well bore are drawn into the separator 50 due to suction of a pump (e.g., submersible pump, sucker rod pump etc.) that draws fluid upward through the interior of the inner pipe 120. As shown, the upper end of the inner pipe 120 exits through the upper end of the separator 50 where it may be connected to a pump. See, e.g., FIG. 2. The production fluids entering the intake slots may include particulates. Once the production fluids enter the intake slots 112 into the interior of the outer casing 100, the fluids and any included particulates proceed downward along a flow path defined by the annulus between an inside surface of the outer casing 100 and an outside surface of the inner pipe 120. See FIG. 3B. The production fluids proceed downward to a pump intake 128 formed by an open bottom end of the inner pipe 66. As shown, the pump intake 128 formed by the lower end of the inner pipe 120 is disposed within the interior (i.e., above the bottom end) of the outer casing 100.

The change in direction of the production fluid from downward movement in the annulus between the outer casing and inner pipe to an upward movement into the pump intake 128 in the bottom of the inner pipe works to separate some particulates from the intake. That is, the downward moving particulates have a momentum that may allow them to proceed past the pump intake despite suction forces existing at the pump intake. To further effect separation of particulates, a fluid directing fin 125 is attached to an outside surface of a lower portion of the inner pipe 120. The fin 125 extends into a spacing (e.g., annulus) between the outer casing 100 and the lower portion of the inner pipe 120. This fin 125 (e.g., helical fin) directs the fluid mixture radially as it moves downward.

The downward velocity of the production fluids and the radial movement caused by the fin 125 works to force particulates in the fluid flow toward the inside surface of the outer casing 100. That is, centrifugal forces move the heavier particulates to the outside edge of the fluid flow moving these particulates away from the opening of pump intake 128. The momentum of the heavier solid particulates in the fluid mixture and their disposition nearer to the inside surface of the outer casing 100 prevents most of the particulates/particles 180 from reversing direction and entering the pump intake 128, thereby allowing the particles 180 to continue through the bottom of the separator into, for example, a mud anchor below the separator. It should also be noted that flow into the pump intake 128 can be managed by altering the speed of the pump depending on, for example, an operator's parameters or constraints from other parameters in the system. By way of example, by altering the relative diameters of the outer casing 100 and the inner pipe 120 the downward velocity of flow path and the upward, or suction velocity of flow path at the pump intake (which may dependent on pump speed) can be controlled better optimizing velocity for the fluid mixture to reduce any vacuum effect at pump intake that would draw particulates into the intake. Generally, it is desirable to insure that the downward velocity of the gas, liquids, and particulates is greater than the upward intake velocity. Once the liquid and gas now mostly or entirely free of particulates have entered pump intake, the mixture is able to move into the inner pipe and travel up to the surface of the well.

As best shown in FIG. 3C, the separator includes a number of individual components. As noted above, the primary components of the separator are the outer casing 100 and the inner pipe 120, which are connected by various connectors. More specifically, the separator 50 includes a coupler 172 that is connected to an upper end of the outer casing 100 that is configured to mate with top fitting 170 that connects to both the coupler 172 and an upper end of the inner pipe 120. The coupler 172 may be a standard pipe collar having internal threads on its upper and lower ends. That is, the upper internal end of the coupler 172 threadedly receives the lower end of the top fitting 170 while the lower end of the coupler 172 engages external threads on upper end of the outer casing 100. Alternatively, the outer casing may be welded to the coupler 172. IN a preferred embodiment, the top fitting 170 threadedly connects to both the inner pipe and the coupler. Further, the top fitting 170 may be threadedly coupled to, for example, production tubing to provide fluid communication between a pump and an interior of the inner pipe 120. A bottom fitting 176 connects to the bottom end of the outer casing 100 permitting connection of additional components (torque anchors, mud anchors, etc.) below the separator 50. Preferably, each of the connections are threaded connections to permit the separator to be assembled and disassembled. Of note, most prior separator devices use a welded connection between the top fitting, the inner pipe and the upper end of the outer casing. Accordingly, if any single component (e.g., outer casing) becomes worn, the entire assembly must be discarded. Utilization of threaded connection between these components permits repairing the separator as needed. That is, individual components may be replaced as needed.

FIG. 4 illustrates a cross-sectional view of the top fitting 170. As shown, the top fitting 170 is an elongated annular connector having a hollow interior that is aligned with the hollow interior of the inner pipe 120 when assembled. The top fitting 170 includes on its lower end a first set of internal threads 192 configured to receive a threaded top 127 of the inner pipe 120 (See, e.g., FIG. 3C). The lower end of the top fitting 170 also includes a set of external threads 194 that are sized for receipt within the coupler 172 attached to the upper end of the outer casing 100. The upper end of the top fitting 170, in the present embodiment, includes a set of external threads 196 the may be attached to, for example, production tubing and/or a pump.

FIG. 5 illustrates a cross-sectional view of the bottom fitting 176. As shown, the bottom fitting 176 is an elongated connector having a hollow interior that is aligned with the interior of the outer casing when connected. The bottom fitting 176 includes a set of external threads 198 on its upper end that are threadedly received within the bottom end of the outer casing 100. A bottom end of the bottom fitting 176 includes a set of external threads 199 which may engage, for example, a mud anchor. In an embodiment, the internal periphery of the upper interior end of the bottom fitting is chamfered 197 to reduce the wear at the connection between the bottom fitting and the lower end of the outer casing 100. More specifically, the chamfered surface 197 reduces wear as particulates pass out the outer casing 100 and into the interior of the bottom fitting.

As previously noted, the threaded connection between all of the components facilitates the assembly and repair of the separator. More specifically, the threaded connection allows for disassembly in the field as well as replacement and/or redressing of any of the components of the separator. That is, the separator may be removed from a well, disassembled, redressed and reused. The ability to redress the separator is of additional importance when the separator is utilized with wells that have undergone hydraulic fracking and are experience high fluid flow, either naturally or by way of artificial lift (e.g., submersible pumps). In such instances, the production streams typically include significant amounts of particulate and the high flow rates result in considerable abrasion due to the particulates. Such abrasion is of particular concern in the lower portion of the separator where the internal fin 125 of the inner pipe 120 imparts a radial flow on the production fluid and particulate mixture. More specifically, centrifugal force imparted due to the radial motion of the fluid disposes the heavier particulates to the outside surface of the flow path. Stated otherwise, the particulates move outward against the inside surface of the outer casing. This results in considerable abrasive wear to the inside surface of the outer casing where the outer casing overlaps the lower portion of the inner pipe 120 having the radial flow inducing fin 125. This portion of the separator typically wears out prior to any other component of the separator.

In an embodiment, the separator is configured to ameliorate effects caused by high production flows having significant particulate content. More specifically, use of a two-piece outer casing design, different materials, and/or a non-uniform thickness of the outer casing provides a separator the may be easily repaired and/or provides improved resistance to abrasive wear. As shown in FIGS. 3A-3C, the illustrated embodiment of the outer casing 100 is formed of first and second connected sections. That is, the outer casing 100 may be formed from an upper tube or barrel 102A and a lower tube or barrel 102B. In such an embodiment, the connected barrels may have differing material properties. In an embodiment, the lower barrel 102B is configured to extend over (e.g., encase, overlap, etc.) the lower portion of the inner pipe 120 that includes the fin 125, which imparts centrifugal motion to the fluid passing downward through the separator between the external surface of the inner pipe 120 and the internal surface of the lower barrel 102B. The lower barrel may be comprised of different (harder) material than that of the upper barrel 102A. Alternatively, the lower barrel 102B may be comprised of heat treated (hardened) material that is the same material as the upper barrel 102B. In such an arrangement, the hardness of the lower barrel 102B (e.g., Brinell Hardness) may be greater than the hardness of the upper barrel 102A.

As best shown in FIGS. 3A and 6, the lower barrel 102B has a sidewall thickness that is greater than the sidewall thickness of the upper barrel 102A. In such an arrangement, the internal diameter ID1 of the upper barrel 102A and the internal diameter ID2 of the lower barrel 102B may be the same. However, this is not a strict requirement. However, the outside diameter OD1 of the upper barrel 102A may be less than the outside diameter OD2 of some or all of a length of the lower barrel 102B. The added thickness of the lower barrel provides improved wear and durability for the section of the separator the experiences the most wear due to the centrifugal motion to the fluid passing downward through the separator. Such improved wear is particularly desirable for use in electric submersible pump systems where fluid flow speeds and volumes are increased (e.g., in relation to rod pumps) and can cause significant wear. Further, the use of separate upper and lower barrels to form the outer casing also facilitates the replacement of the lower barrel when needed. Along these lines, it will be noted that the upper barrel typically includes more machining (e.g., inlets) and the ability to replace only the lower barrel provides some efficiencies in reusing more complex parts.

Though discussed as utilizing an upper barrel and lower barrel that are connected, it will be appreciated that the outer casing may be formed from a single tube. In such an arrangement, the sidewall thickness may vary over the length of the single tube while an internal diameter of the single tube may be uniform over its length.

The foregoing description has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the inventions and/or aspects of the inventions to the forms disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the presented inventions. The embodiments described hereinabove are further intended to explain best modes known of practicing the inventions and to enable others skilled in the art to utilize the inventions in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the presented inventions. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art. 

What is claimed is:
 1. A particulate separator for disposition within a well casing of a petroleum production well producing a fluid mixture including particulate matter, the separator comprising: an outer casing including intake apertures, proximate an upper end of the outer casing, allowing the fluid mixture to enter the outer casing; an inner pipe disposed within the outer casing, wherein an upper outlet of the inner pipe exits through the upper end of the separator and a lower end of the inner pipe is disposed proximate to a lower end of the outer casing; a fin disposed on a lower portion of the inner pipe, wherein fluid flows downward between the interior of the outer casing and an exterior of the inner pipe, wherein the fin imparts a radial path to the fluid as it moves toward a pump intake defined by the lower end of the inner pipe, wherein, a lower portion of the outer casing that encases the fin on the lower portion of the inner pipe has at least a first material property that is different than a material property of an upper portion of the outer casing that encases an upper portion of the inner pipe that free of the fin.
 2. The separator of claim 1, wherein the material property comprises one of: a sidewall thickness; a hardness; and a material type.
 3. The separator of claim 1, wherein a sidewall thickness of the outer casing varies over its length.
 4. The separator of claim 3, wherein the sidewall thickness of the lower portion of the outer casing is greater than a sidewall thickness of the upper portion of the outer casing.
 5. The separator of claim 3, wherein the outer casing comprises: an upper barrel forming the upper portion of the outer casing; and a lower barrel forming the lower portion of the outer casing.
 6. The separator of claim 5, wherein the lower barrel and the upper barrel are threadedly connected.
 7. The separator of claim 1, further comprising: an elongated hollow connector having: a first set of threads configured to connect to mating threads on an upper end of the inner pipe; and a second set of threads configured to connect to mating threads on an upper end of the outer casing.
 8. The separator of claim 7, wherein the first set of threads and the second set of threads are disposed on a first end of the elongated hollow connector, the elongated hollow connector further comprising: a third set of threads disposed on a second end of the elongated hollow connector.
 9. The separator of claim 1, further comprising: a hollow bottom fitting having: a first set of threads on a first end of the hollow bottom fitting configured to connect to mating threads on a lower end of the outer casing; and a second set of threads on a second end of the hollow bottom fitting.
 10. The separator of claim 9, internal periphery of the upper interior end of the hollow bottom fitting comprises a chamfered surface.
 11. A particulate separator for disposition within a well casing of a petroleum production well producing a fluid mixture including particulate matter, the separator comprising: an outer casing having: an upper barrel having at least a first intake aperture disposed through a sidewall of the upper barrel proximate an upper end of the upper barrel; a lower barrel having an upper end attached to a lower end of the upper barrel, wherein hollow interiors of the upper barrel and lower barrel are aligned to define a hollow interior the outer casing; an inner pipe disposed within the hollow interior of the outer casing, the inner pipe extending from an upper end disposed proximate to an upper end of the outer barrel to an open lower end disposed within a lower portion of the lower barrel, wherein a space between the inside surface of the outer casing and an outside surface of the inner pipe defines a flow path between the intake aperture and the open lower end of the inner pipe; and a fin disposed on a lower portion of the inner pipe, wherein the fin imparts a radial path to the fluid as it moves along the flow path toward the open end of the inner pipe, wherein the lower barrel overlaps the lower portion of the inner pipe and the fin.
 12. The separator of claim 11, wherein a sidewall thickness of the lower barrel is greater than a sidewall thickness of the upper barrel.
 13. The separator of claim 12, wherein an inside diameter of the upper barrel is substantially equal to an inside diameter of the lower barrel.
 14. The separator of claim 11, wherein the lower barrel is formed from a first material and the upper barrel is formed form a second material, wherein the first and second materials are different.
 15. The separator of claim 11, further comprising: an elongated hollow connector having: a first set of threads configured to connect to mating threads on an upper end of the inner pipe; and a second set of threads configured to connect to mating threads on an upper end of the upper barrel of the outer casing.
 16. The separator of claim 17, wherein the first set of threads and the second set of threads are disposed on a first end of the elongated hollow connector, the elongated hollow connector further comprising: a third set of threads disposed on a second end of the elongated hollow connector.
 17. The separator of claim 1, further comprising: a hollow bottom fitting having: a first set of threads on a first end of the hollow bottom fitting configured to connect to mating threads on a lower end of the lower barrel of the outer casing; and a second set of threads on a second end of the hollow bottom fitting.
 18. The separator of claim 17, internal periphery of the upper interior end of the hollow bottom fitting comprises a chamfered surface.
 19. The separator of claim 11, wherein an upper outlet of the inner pipe exits through an upper end of the separator.
 20. The separator of claim 11, further comprising: a plurality of intake apertures disposed about a periphery of the sidewall of the upper barrel. 